Process of manufacturing filaments for incandescent lamps



uw Mdeyx.) l Y y A. DE LODYGUINB.v PROCESS 0F MANUFACTURING PILAMENTS FOR INGANDBSCBNT LAMPS.

No'. 494,149. Patented'lVIar. 28, 1893.

'LUNITED? STATES PATENT OFFICE.

ALEXANDRE DE 'LCDYGUINE CE PARIS, FRANCE, AsSICNoR, BY MEsNE ASSIGNMENTS, To TIIE wEsTINeIIoUsE ELECTRIC 4AND MANUFACTUR- ING COMPANY, or PITTSRURG, PENNSYLVANIA.

PROCESS OF MANUFACTURING FILAMENTS FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 494,149, dated March 28, 1893. Application filed September 14, 1888. Serial No. 285.432. (N9 specimens.)

to expose them to the action of the -'uoride .of boron, as hereinafter described. Fig. 3 is a View of the apparatus in which the blanks are exposed to the action -of the Iiuorid'e of boron.

My invention relates particularly to the process of manufacturing the incandescents or iilaments. Imakeuse of any suitable organic substances, such as bamboo, paper, thread,

piassava, or anyv other organic material capable of the treatment hereinafter mentioned.

The organic-material used is reduced to the required shape and size in any'of the well known ways for making the iilaments or blanks` from which such incandescente are made. -These blanks A, having the required dimensions are bent upon a suitable form or block of lead B, Fig. 1, to give them the required finished shape, and they are fastened upon such block in any desired way, such, for

instance, as inserting their free ends into a suitable recessv or .crease C, in the side or edge ofthe block, which recess is closed on the ends of the blank tohold it in place. The

form B, having the blank secured to it, is

placed in a closed vessel in which itis exposed to the action of iiuoride of boron (BFIS). In Fig. 3 I show a form of vessel D, which may be used for this purpose. It is lined internally with lead to resist the action of the fluoride of boron, audit has a grating E, upon which the blocks E, withthe incandesceuts secured thereto, are placed. The chemicals from which the uoride is produced are placed in the lower part of the vessel. The gas arising therefrom acts upon the blankssecured to the forms B, and carbonizes them, driving oi the elements of water chemically combined therewith, preserving the original form and structure of the blanksand imparting to them a homogeneous character, with the exception that the fluoride will combinew'ith any foreign lnineral substances which maybe contained in the material, forming uoride salts.

A neckor tube F, leads from the retort D, and terminates in a glass vessel G, which is illed with naahtha or other liquid not containing the elements of water, so that the gas will not combine therewith. The end of the tube so that the latter kacts as a seal. The trap thus made, while permitting the gas to pass through, eectually seals the 'retort against the entrance of the atmosphere, and so prevents the strength of the fluoride of boron from being wasted upon the moisture in the atmosphere. with a filling orifice Il, through which the naphtha'is poured into it. It is also vprovided with an 'outlet I, from which a neck or-tube K leads to a second vessel L containing water, said vessel being also provided with an exit opening M, communicating with the atmosphere. The ends of the tube K terminate above the surfaceof the liquids contained in the vessels G and L, and the gas passing through the liquid contained in the vessel G, escapes therefrom through the pipe K into the vessel L, where it combines with the water. The water is capable of absorbing the gas up tothe limit of eight hundred volumes of gas to one of water. The opening M prevents the accumulation of pressure in the vessel L. lhe gas is destructive of life, and the object ofthe vessel L is to render it'harmless by providing for its absorption. rlhe liquid contained in the vessel L after the absorption of the gas is an acid which canbe used for etching glass. Without the provision of the vessel L, the pipe K should lead to a stack the lower end of the retort D, forthe purpose of heating the chemicals to produce the fluoride of boron. The heat in the retort should not be less than 300 and not more than 570 The glass vessel G is provided F, terminates below the surface of the liquid,

Fahrenheit. The degree of heatl is deter# mined by a thermometer O, and the gas flame roo is regulated by a cock P. It is not necessary that the incandescents should be treated in the same vessel in which the gas is produced, but, if desired, the gas may be produced in one vessel and then lcd to another vessel in which the incandescents are placed, as will be readily understood.

In order to prevent the liquid inthe vessel G from being forced into the retort D by the atmospheric pressure, when after the completion of the process, the retort I) is being cooled, a bulb Q is provided in the pipe F, of sufficient capacity to contain all the liquid in the vesselr G, so that when the latter is forced up the pipe by the atmospheric pressure it will fill the bulb and be arrested thereby. In order to prevent danger t0 the workmen from the gas when the retort D is open, after the completion of the process, a'branch pipe S, communicating with the pipe F, is provided. lhis branch pipe leads to a vessel 'l containlng water, and is providedl withla suitable cock. Before opening theretort D, the workman opens the cock so asto permit the gas to communicate with the water in the vessel, which will be of sufiicient quantity to absorb the gas remaining in the retort D, so that when the retort is opened it will contain no gas injurious to the workmen.

Lead is used in formingthe block li, because it is not affected by the fluoride of boron.

After this step inthe operation, the incandescents are removed fromfthe blocks B,`and they are then placed in an airtight erucible and covered with graphite-or powdered carbon, and the erueible lis placed ina furnace and, exposed to a high temperature for the purpose of eliminating from the incandescents any fluoride which may remain uncombined, as well as the chemical combinations which may have formed upon them, and also'any other gases or Vsubstances contained therein, which can be removed by the heat'of the furnace. Heat can be conveniently, obtained by the u se of a gas furnace, and a gradually increaslng temperature shouldebe applied, say,

during aperiod of about thirty minutes,

until the highest' temperature is reached, which may be continued about two hours and then gradually reduced until the furnace is cold. When the erncible is sucient-ly cold the incandescents are removedV therefrom and attached to temporary clamps or elecv trodes and placed in a suitable chamber, from which the air has been removed, and there heated to a veryhigh heat 'in vacuo by passing a current of electricity through them. 'lhe incandescent in this operation should be exposed to as high a heat as itis capable Aof withstanding without fracture. The purpose of this step of theoperation is to drive olf all occluded gases from the incandescent and to complete the carbonizing operation. '1`he perfect treatment by the lluoride has the elect of increasing the'abilitv of the incandescent to withstand heat, and

the effect of subsequent super-heatingbyA means of the electric current is t0 change the rather friablc carbon of the incandescent thus obtained into ahighly refractory homogeneous coke in which the form and structure of the original blank are preserved. During this step of the operation the atmosphere of thechamber is being continually drawn oli, so that the gases which are expelled from the incandescent by the high heat shall be carried away from and out of the chamber. It is better to admit a small quantity of illuminating gas or other suitable gas into the chamber before the beginning of this step of the process, for the purpose of reducing the amo'unto'f oxygen' contained in the chamber, as the effect of the admission of the gas is to reduce the quantity of atmospheric ai r which may be present. This operation of heating by means of an electric current occupies but a short time, being in the case of ordinary sized incandescents vfrom thirty seconds to two min ntes. removed from the temporary clamps or hold- 'lhe 'incandcscents are then ers and so much ofthe ends as were not fully exposed to the high heat of the electric current, may be lbroken off. After this the incandescents are secured to the platinum clamps or holders which constitute their permanent electrodes in the finished lamp, and placed in a receiver from which the atmosphere is exhausted and to which an atmosphere o'f earbonaceous gas not containing oxygen, say for instance, gasoline or rhigoline, is admitted. An electric current is then passed through the incandescent for the purpose of building it up by the deposition of the IOO carbon, and thereby imparting to it a uniform resistance. This step ofV the process does not differ from that usually practiced in the manufacture of fibrous filaments for in candescent lamps, except that it follows instead of preceding the operation of driving,

olf the occluded gases. The advantage of driving ott the occluded gases before the process'of building up the carbon by deposition 'llO is that 'if the latter operation is first performed, the hard deposit or shell thereby made upon the incandescent, has a tendency to prevent the escape of the gases, so that a greater or less quantity remains in the incandescent, and the effect of their presence is to endanger the incandescent, and to increase the blaekening of the bulb of the lamp when in use and shorten its life. The incandescent is then taken and sealed into the lamp bulb in the usual way, and the latter is either exhausted or filled with an artificial atmosphere inv the way practiced in the manu facture of incandescent lamps. 'lhe incandescent maybeheatedby an electric currentwhile the bulb`- is being evacuated, in the usual way.

' I have referred somewhat to the constructionof apparatus used in'this process and also to periods' of time which may be occupiediby somev of the steps, 4but I do not limit .myself to any particular form of apparatus.

orto any particular periods of time in the various operations. These things, together with the form, and-construction of the apparatus which is used in the process, will be readily understood by persons familiar with the art, and it is not necessary to cucumber' this specification with any further description of or reference to them.

The action ofthe fluoride of boron is to decompose the organic substance composing the incandescent by dehydrating it, leaving practicallyT nothing, in the case of a vegetable material, butthc carbon with which it has no chemical aiinity, and in the case of an animal substance, leaving only the carbon and nitrogen.

There are other chemical agents, known to chemists which have such an aiiinity to Water that they will decompose and carbonize organic substances, among which agents are sulphuric acid, uohydric acid, chlorine gas,

caustic soda, and caustic potash. Such cheinical agents are more or less adapted to use in my improved method, and I include them in my claimas the chemical equivalents of the fluoride of boron, although not so powerful for the purpose. The manner of using them to dehydrate and decompose -organic substances is familiar tothe skillful chemist and need not be here described.-

The advantages of my improved process consist in the fact that the incandescents are very free from a tendency to -blacken the lamp when in use, and require withthe same life and candle-power a smaller expenditure of energy than incandescents made by any other process heretofore known to me. Now, what I claim as my invention, and desire to secure by Letters Patent, is

The process of making carbon ilaments or` incandescents for electric lamps from organic material, which consists in the following steps, viz: dehydrating and decomposing the incandescents by the action of a chemical agent;

then subjecting them to a high temperature with the exclusion of oxygen; then expelling 1 the occluded gases from the incandescents and coking them by subjecting them to a high temperature by the passage of an electric current; and finally giving them the required resistance by the deposition of carbon; substantially as described.

In testimony whereof I have hereunto subscribed my name this 9th day of August, A. D. 1888.

ALEXANDRE DE LODYGUINE.

Witnesses;

W. D. UPTEGRAFF, y CHARLES A. TERRY. 

